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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2008-06-27 13:41:16 +0200
committerIngo Molnar <mingo@elte.hu>2008-06-27 14:31:31 +0200
commit103638d95ba5b0c53c8d9c0cb581156ccc8513ee (patch)
tree56d78e3e00780e044ef7688f27c93ece813035c1 /kernel/sched_fair.c
parent76a2a6ee8a0660a29127f05989ac59ae1ce865fa (diff)
downloadblackbird-op-linux-103638d95ba5b0c53c8d9c0cb581156ccc8513ee.tar.gz
blackbird-op-linux-103638d95ba5b0c53c8d9c0cb581156ccc8513ee.zip
sched: fix wakeup granularity and buddy granularity
Uncouple buddy selection from wakeup granularity. The initial idea was that buddies could run ahead as far as a normal task can - do this by measuring a pair 'slice' just as we do for a normal task. This means we can drop the wakeup_granularity back to 5ms. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_fair.c')
-rw-r--r--kernel/sched_fair.c15
1 files changed, 7 insertions, 8 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 183388c4dead..509092af0330 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -63,13 +63,13 @@ unsigned int __read_mostly sysctl_sched_compat_yield;
/*
* SCHED_OTHER wake-up granularity.
- * (default: 10 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ * (default: 5 msec * (1 + ilog(ncpus)), units: nanoseconds)
*
* This option delays the preemption effects of decoupled workloads
* and reduces their over-scheduling. Synchronous workloads will still
* have immediate wakeup/sleep latencies.
*/
-unsigned int sysctl_sched_wakeup_granularity = 10000000UL;
+unsigned int sysctl_sched_wakeup_granularity = 5000000UL;
const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
@@ -813,17 +813,16 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
se->prev_sum_exec_runtime = se->sum_exec_runtime;
}
-static int
-wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
-
static struct sched_entity *
pick_next(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
- if (!cfs_rq->next)
- return se;
+ struct rq *rq = rq_of(cfs_rq);
+ u64 pair_slice = rq->clock - cfs_rq->pair_start;
- if (wakeup_preempt_entity(cfs_rq->next, se) != 0)
+ if (!cfs_rq->next || pair_slice > sched_slice(cfs_rq, cfs_rq->next)) {
+ cfs_rq->pair_start = rq->clock;
return se;
+ }
return cfs_rq->next;
}
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